James Dixon rejecting the Bering bridge theory

Combined with ecological and genetic evidence, the findings support the notion that the settled in the Bering Strait region for a while before migrating into North America.

Humans May Have Been Stuck on Bering Strait for …

Land Bridge Theory and Watercraft Migration Theory …

Other than humans, rhesus macaques are Earth’s most widespread primates, and both species are generalists whose ability to adapt has been responsible for their success. Rhesus macaques are , about twice that of dogs and cats, and nearly as much as chimpanzees. Rhesus macaques have what is called Machiavellian social organization, in which everybody is continually vying for rank and power is everything. Those with rhesus power get the most and best food, the best and safest sleeping places, mating privileges, the nicest environments to live in, and endless grooming by subordinates, whom the dominants can beat and harass whenever they want, while those low in the hierarchies get the scraps and are usually the first to succumb to the vagaries of rhesus life, including predation. It is the . But even the lowliest macaque will become patriotic cannon fodder if his society faces an external threat, as even a macaque knows that a miserable life is better than no life at all. The violence inflicted seems economically optimized; within a society the violence is mostly harassment, but when rival societies first come in contact, the violence is often lethal, as the initially established dominance can last for lifetimes. Within a society, killing a subordinate does not make economic sense, as that subordinate supports the hierarchy. Potentates rely on slaves. The human smile evolved from the teeth-baring display of monkeys that connotes fear or submission.

Land Bridge Theory and Watercraft Migration ..

For all of their seeming cunning and behaviors right out of , rhesus monkeys cannot pass the ; they attack their images, as they see themselves as just another rival monkey. Chimpanzees, on the other hand, pass the mirror test, and the threshold of sentience, whatever sentience really is, may not be far removed from the ability to pass the mirror test, or perhaps humanity has not yet achieved it. , considered the most intelligent New World monkeys, have socially based learning, in which the young watch and imitate their elders. Different capuchin societies have different cultures and different tool-using behaviors reflected in different solutions to similar foraging problems. Capuchins, isolated from African and Asian monkeys for about 30 million years, have striking similarities to their Old World counterparts, with female-centric societies and lethal hierarchical politics. As with chimpanzees and humans, ganging up on lone victims is the preferred method, which increases the chance of success and reduces the risk to the murderers. Unlike rhesus monkeys, for instance, capuchin males can help with infant rearing, but they will also kill infants that they did not father, as rhesus, also do (that behavior has been observed in 50 primate species). Those comparisons provide evidence that simian social organization results from the connection between simian biology and environment; their societies formed to solve the problems of feeding, safety, and reproduction.

The Beringia Theory or commonly called the …

But the branch of the that readers might find most interesting led to humans. Humans are in the phylum, and the last common ancestor that founded the Chordata phylum is still a mystery and understandably a source of controversy. Was our ancestor a ? A ? Peter Ward made the case, as have others for a long time, that it was the sea squirt, also called a tunicate, which in its larval stage resembles a fish. The nerve cord in most bilaterally symmetric animals runs below the belly, not above it, and a sea squirt that never grew up may have been our direct ancestor. Adult tunicates are also highly adapted to extracting oxygen from water, even too much so, with only about 10% of today’s available oxygen extracted in tunicate respiration. It may mean that tunicates adapted to low oxygen conditions early on. Ward’s respiration hypothesis, which makes the case that adapting to low oxygen conditions was an evolutionary spur for animals, will repeatedly reappear in this essay, as will . Ward’s hypothesis may be proven wrong or will not have the key influence that he attributes to it, but it also has plenty going for it. The idea that fluctuating oxygen levels impacted animal evolution has been gaining support in recent years, particularly in light of recent reconstructions of oxygen levels in the eon of complex life, called and , which have yielded broadly similar results, but their variances mean that much more work needs to be performed before on the can be done, if it ever can be. Ward’s basic hypotheses is that when oxygen levels are high, ecosystems are diverse and life is an easy proposition; when oxygen levels are low, animals adapted to high oxygen levels go extinct and the survivors are adapted to low oxygen with body plan changes, and their adaptations helped them dominate after the extinctions. The has a pretty wide range of potential error, particularly in the early years, and it also tracked atmospheric carbon dioxide levels. The challenges to the validity of a model based on data with such a wide range of error are understandable. But some broad trends are unmistakable, as it is with other models, some of which are generally declining carbon dioxide levels, some huge oxygen spikes, and the generally relationship between oxygen and carbon dioxide levels, which a geochemist would expect. The high carbon dioxide level during the Cambrian, of at least 4,000 PPM (the "RCO2" in the below graphic is a ratio of the calculated CO2 levels to today's levels), is what scientists think made the times so hot. (Permission: Peter Ward, June 2014)

29/04/2009 · Land Bridge Migration Theory ..

But the most impressive dual-use innovation in mollusks is what cephalopods invented. Their gill pumps are quite muscular and . That . Jet propulsion is not an energy-efficient means of transportation, but the cephalopod’s ability to pass oxygen-bearing water over its gills is unmatched. Cephalopods can live in waters too hypoxic for fish to survive. In the coming Ordovician Period, cephalopods would be apex predators of marine biomes and would hold that distinction for a long time. Cephalopods are today’s ; the and it has the largest brain-to-body-size ratio of all invertebrates. It is thought that the skills needed for predation stimulated cephalopodan intelligence. Today, the is the only survivor of that lineage of Ordovician apex predators.

“From the north-west via Beringia, ..

Deep-ocean currents, , do not seem to have existed during supercontinental times, and atmospheric oxygen was likely only a few percent at most when the Cryogenian Period began. Canfield’s ocean-oxygenation evidence partly came from testing sulfur isotopes. As with , , and other elements, life prefers the lighter isotope of sulfur, and are two stable isotopes that can be easily tested in sediments. Canfield proposed that in pre-Cryogenian oceanic depths, , which are among Earth’s earliest life forms and produce as its waste product, abounded. Hydrogen sulfide gives rotten eggs their distinctive aroma and is highly toxic to plants and animals, as it . Hydrogen sulfide would react with dissolved iron to form iron pyrite and settle out in the ocean floor, just as the iron oxide did that formed the BIFs. The sulfate-reducing bacteria will enrich the sulfur-32/34 ratio by 3% and did so before the Cryogenian, but the Ediacaran iron pyrite sediments showed a 5% enrichment. A persuasive explanation is recycling sulfur in the oceanic ecosystem, which can only happen in the presence of oxygen.

Beringia Ice Age Migration Hypothesis #1

There is great controversy regarding how violent Neanderthals were and how much Cro-Magnons hastened their demise, but there is no doubt that sophisticated stone tools were used for far more than hunting mammoths. A Gravettian child’s vertebra was found with a projectile point lodged in it. Flint blades and projectile points lodged in vertebrae and other bones, and skulls broken by stone weapons, are common finds in Stone Age graves around the world. Before the Paleolithic Era’s end about 12 kya, cave paintings depict torture, people pin-cushioned with arrows, and other violent scenes. In 1964, , which has been dated to about 13 kya. Such finds are increasingly common, and are often situated near coveted resources such as riverbanks. The Golden Age of the Hunter-Gatherer was long gone by 15 kya in the Eastern Hemisphere but would briefly flourish again in the last continents that humans conquered. Here is a map, based on DNA analysis, of the dates of human migration to the Americas. (Source: Wikimedia Commons)

Linguistic Phylogenies Support Back-Migration from Beringia ..

Except for New Guinean highlanders, initial European contact with all of those relict populations was universally disastrous, just as and elsewhere for centuries. Those initial contacts happened in anthropology’s early days, and studied the Andamans in the early 20th century, when they were tattered remnants of the people of a century earlier. The people were also devastated by European invasion. When the Dutch invaded what became South Africa, the Southern San were driven to extinction while the !Kung survived in the . Andamans, !Kung, and Aboriginal Australians all had/have strikingly similar religious ceremonies, which were marathon singing and dancing sessions that could last all night. Some rituals lasted for months. Their rituals are very likely what the first religions looked like, which were strenuous ordeals in which people reached frenzied states that left them exhausted. Today’s leading hypothesis is that those rituals created group cohesion that held their society together. The social glue of monkey and ape societies is grooming, but humans seem to have , and those early rituals further cemented the bonds.